During fabrication of a semiconductor device, chemical mechanical planarization (CMP) is performed to smooth surfaces of the semiconductor device using chemicals and/or mechanical forces. For example, the semiconductor device can be polished to prepare the semiconductor device for a new layer of material. In one example of polishing, the semiconductor device can be secured to a polishing head configured to hold and rotate the semiconductor device. The polishing head can rotate the semiconductor device against a polishing pad, which can also be rotating, to apply mechanical force to the semiconductor device to remove material and/or even out irregular topography of the semiconductor device, for example. In one example, chemicals, such as slurry (e.g., colloid), can be applied to the polishing pad during polishing to serve as solvents which aid in reducing non-uniformities on the surface of the semiconductor device.
Additionally, during fabrication of a semiconductor device, etching, such as chemical etching, is performed to remove material from the semiconductor device. Chemical etching is selective, such that different etch chemistries remove different materials. For example, one etch chemistry removes silicon oxide but not silicon nitride.